Hydrologic routing of runoff from upstream locations is a central element in rainfall-runoff modeling. Channel cross-section geometry is used to develop routing parameters for this process. The sensitivity of the routed peak discharge to cross-section location along the routing reach is examined using two methods in this thesis. First, an enumeration method was used to analyze the sensitivity of overall peak discharge to the channel routing process by executing the TR-20 model for all possible cross-section locations evaluated within the GIS. Second, a regression equation as a function of the modified att-kin method routing coefficient, reach length, and channel slope shows promise as a planning and decision making tool when implementing the rainfall-runoff model. Finally, case study analyses support the usefulness that a possible future expert system would provide for guidance on developing routing reach cross-section characteristics to engineers and other professionals that use GIS to perform hydrologic rainfall-runoff modeling.